J.C.
I would talk to the doctor. Maybe s/he'll have some suggestions. Also get it 'on the record' as an issue. I know a long time ago my mom was telling me that one of her cousins did this and one time he got a fever and back then they put them in ice water to bring it down, all of those old bruises showed up and CPS was called. Luckily they had on file with the doctor his history of beating his head against the wall. Dont want to scare you - just an fyi if you hadnt thought of it!
Good luck I hope someone has some answers for you